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String to image

version (5.67 KB) by Serge
Convert text string to image


Updated 25 Jan 2017

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Convert text string to rgb image
str2im - display example text
str2im(str) - text as char array or cellstr
str2im(str,pad) - margin: [N] or [H V] or [L R T B] as pixels or nan
str2im(...,props) - text property as value pairs, doc text
I = str2im(..) - returns rgb image data as uint8
[I,A] = str2im(..) - returns background alpha channel as uint8
[I,A,H,W] = str2im(..) - returns image height and width

-If a margin is nan then the background is cropped up to the text.
-A bit slow because nothing is cached, a figure is generated for each
call and getframe is used, usually take more then 0.03s to run.
-Windows start menu may occlude text if it is not at bottom of screen or
greater then 60 pixels in height.
-Maximum image size is limited by screen resolution: [V_rez-60 H_rez].

Useful text properties:
BackgroundColor - {w} y m c r g b k [r g b]
Color - {k} y m c r g b w [r g b]
FontSize - {20} positive number
FontUnits - {points} pixels normalized inches centimeters
FontWeight - {normal} bold light demi
FontAngle - {normal} italic oblique
FontName - Helvetica FixedWidth ... (see listfonts)
Interpreter - {none} tex latex
HorizontalAlignment - {left} center right

System defaults:
get(0,{'defaultTextFontName' 'FixedWidthFontName'})

figure(1),clf, str2im({'str' '2im'},nan,'back','y','fontw','b','hor','c')
figure(2),clf, str2im('\phi_k^\pi',[0 0 -22 -10],'fonts',40,'interp','t')
figure(3),clf, str2im('$$\int_0^2x^2\sin(x)dx$$','col','b','interp','l')

Example: burn text into image
[T,A,H,W]=str2im(datestr(now),'fontn','FixedWidth','col','y','back',[.2 .2 .2]);

Example: find fixed-width fonts

Example: show font browser gui
s = uicontrol('sty','edi','pos',[ 5 5 150 50],'str',char(reshape(32:127,[],6)'),'max',1000);
n = uicontrol('sty','pop','pos',[155 5 150 20],'str',['FixedWidth';sort(listfonts)]);
w = uicontrol('sty','pop','pos',[305 5 60 20],'str',{'normal' 'bold' 'light' 'demi'});
a = uicontrol('sty','pop','pos',[365 5 60 20],'str',{'normal' 'italic' 'oblique'});
c = uicontrol('sty','pop','pos',[425 5 40 20],'str',{'k' 'y' 'm' 'c' 'r' 'g' 'b' 'w'});
b = uicontrol('sty','pop','pos',[465 5 40 20],'str',{'w' 'y' 'm' 'c' 'r' 'g' 'b' 'k'});
z = uicontrol('sty','pop','pos',[505 5 40 20],'str',cellstr(num2str((1:200)')),'val',20);
F = @(v,i)v{i}; F = @(h)F(get(h,'str'),get(h,'val')); %function to get popup str
set([n w a c b z],'call',@(x,y)str2im(get(s,'str'),'fontn',F(n),'fontw',...

See also: text, getframe, listfonts, rgb2gray, im2double
Serge 2016, for corrections or suggestions email:
Tested on R2010b Win, R2012a Win, more testing feedback is desired

Cite As

Serge (2021). String to image (, MATLAB Central File Exchange. Retrieved .

MATLAB Release Compatibility
Created with R2010b
Compatible with any release
Platform Compatibility
Windows macOS Linux

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